RTC Transit is one of five transit agencies that operate double-decker buses in the United States for fixed-route services, the others being Unitrans of Davis, California; Community Transit of Snohomish County, Washington; Antelope Valley Transit Authority of Palmdale, California and Lancaster, California; and SLO Transit of San Luis Obispo, CA.
Unitrans (the student-run transit service of University of California, Davis, known for years for its operation of former London Transport double-decker buses) ordered two Enviro500 which were delivered in early 2010; these are the first batch of Enviro500s with the bodywork assembled by ElDorado National.
Their purchase signalled the start of a move by Unitrans to a CNG fueled bus fleet, with the purpose of reducing exhaust emissions.